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Arvind Varsani - One of the best experts on this subject based on the ideXlab platform.
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ICTV Virus Taxonomy Profile: Geminiviridae
Journal of General Virology, 2017Co-Authors: F. Murilo Zerbini, Rob W Briddon, Ali M. Idris, Darren P. Martin, Philippe Roumagnac, Rafael F. Rivera-bustamante, Enrique Moriones, Jesús Navas-castillo, Arvind VarsaniAbstract:The geminiviruses are a family of small, non-enveloped viruses with single-stranded, circular DNA genomes of 2500–5200 bases. Geminiviruses are transmitted by various types of insect (whiteflies, leafhoppers, treehoppers and aphids). Members of the genus Begomovirus are transmitted by whiteflies, those in the genera BeCurtovirus, Curtovirus, Grablovirus, Mastrevirus and TurnCurtovirus are transmitted by specific leafhoppers, the single member of the genus Topocuvirus is transmitted by a treehopper and one member of the genus Capulavirus is transmitted by an aphid. Geminiviruses are plant pathogens causing economically important diseases in most tropical and subtropical regions of the world. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Geminiviridae which is available at www.ictv.global/report/geminiviridae.
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Capulavirus and Grablovirus: two new genera in the family Geminiviridae.
Archives of Virology, 2017Co-Authors: Arvind Varsani, Rob W Briddon, Philippe Roumagnac, Rafael F. Rivera-bustamante, Enrique Moriones, Jesús Navas-castillo, Marc Fuchs, Ali Idris, F Murilo Zerbini, Darren P. MartinAbstract:Geminiviruses are plant-infecting single-stranded DNA viruses that occur in most parts of the world. Currently, there are seven genera within the family Geminiviridae (BeCurtovirus, Begomovirus, Curtovirus, Eragrovirus, Mastrevirus, Topocuvirus and TurnCurtovirus). The rate of discovery of new geminiviruses has increased significantly over the last decade as a result of new molecular tools and approaches (rolling-circle amplification and deep sequencing) that allow for high-throughput workflows. Here, we report the establishment of two new genera: Capulavirus, with four new species (Alfalfa leaf curl virus, Euphorbia caput-medusae latent virus, French bean severe leaf curl virus and Plantago lanceolata latent virus), and Grablovirus, with one new species (Grapevine red blotch virus). The aphid species Aphis craccivora has been shown to be a vector for Alfalfa leaf curl virus, and the treehopper species Spissistilus festinus is the likely vector of Grapevine red blotch virus. In addition, two highly divergent groups of viruses found infecting citrus and mulberry plants have been assigned to the new species Citrus chlorotic dwarf associated virus and Mulberry mosaic dwarf associated virus, respectively. These species have been left unassigned to a genus by the ICTV because their particle morphology and insect vectors are unknown.
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Revisiting the classification of Curtoviruses based on genome-wide pairwise identity
Archives of virology, 2014Co-Authors: Arvind Varsani, F. Murilo Zerbini, Cecilia Hernández-zepeda, Ali M. Idris, Darren P. Martin, Enrique Moriones, Jesús Navas-castillo, Judith K. BrownAbstract:Members of the genus Curtovirus (family Geminiviridae) are important pathogens of many wild and cultivated plant species. Until recently, relatively few full Curtovirus genomes have been characterised. However, with the 19 full genome sequences now available in public databases, we revisit the proposed Curtovirus species and strain classification criteria. Using pairwise identities coupled with phylogenetic evidence, revised species and strain demarcation guidelines have been instituted. Specifically, we have established 77 % genome-wide pairwise identity as a species demarcation threshold and 94 % genome-wide pairwise identity as a strain demarcation threshold. Hence, whereas Curtovirus sequences with >77 % genome-wide pairwise identity would be classified as belonging to the same species, those sharing >94 % identity would be classified as belonging to the same strain. We provide step-by-step guidelines to facilitate the classification of newly discovered Curtovirus full genome sequences and a set of defined criteria for naming new species and strains. The revision yields three Curtovirus species: Beet curly top virus (BCTV), Spinach severe surly top virus (SpSCTV) and Horseradish curly top virus (HrCTV).
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Intergeneric recombination between a new, spinach-infecting Curtovirus and a new geminivirus belonging to the genus BeCurtovirus: first New World exemplar
Archives of Virology, 2013Co-Authors: Cecilia Hernández-zepeda, Arvind Varsani, Judith K. BrownAbstract:A novel Curtovirus, spinach severe curly top virus (SSCTV), was associated with symptomatic spinach plants collected from a commercial field in south-central Arizona during 2009. In addition, a second viral molecule of about 2.9 kb from the same spinach plants was amplified, cloned and sequenced. The latter isolate, herein named spinach curly top Arizona virus (SCTAV), was found to share 77 % pairwise sequence identity with beet curly top Iran virus (BCTIV), a leafhopper-transmitted geminivirus that has been assigned to the new genus BeCurtovirus . The SCTAV genome encodes three viral-sense genes, V1, V2, and V3, and two complementary-sense genes, C1 and C2. There was no evidence for the presence of either a C3 or C4 ORF in the genome sequence. The genome organization of SCTAV is not like that of New World Curtoviruses but instead is similar to that of BCTIV, which, to date, is only known to be present in Iran. Consistent with this observation, SCTAV and BCTIV both contain the unusual nonanucleotide TAAGATT/CC and a replication-associated protein, Rep (or C1), that is more closely related to the mastrevirus Rep than to those of Curtoviruses reported to date. Both SSCTV and SCTAV were found to have a recombinant genome containing sequences (AY548948) derived from ancestral SCTV sequences in the virion-sense portions of the genome. Agroinoculation of Nicotiana benthamiana (Domin) plants with the cloned genome of SCTAV resulted in infection of 95 % of the plants and the development of severe curling symptoms, whereas only 20 % of the SSCTV-inoculated plants were infected, developing only mild curling symptoms. When plants were co-inoculated with both viruses, the frequency of infection remained higher for SCTAV than for SSCTV (80 % vs. 20 %), indicating no evidence of synergistic effects between the two viruses with respect to efficiency of infection.
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Genetic diversity and host range studies of turnip curly top virus
Virus genes, 2012Co-Authors: Sara Razavinejad, Jahangir Heydarnejad, Mehdi Kamali, Hossain Massumi, Simona Kraberger, Arvind VarsaniAbstract:Turnip curly top virus (TCTV) is a unique ge- minivirus that has recently been characterised as infecting turnips in Iran. The genome of TCTV shares \68 % pair- wise identity with other geminiviruses and has a genome organisation similar to that of Curtoviruses and topocuvirus. The replication-associated protein (Rep) bears the highest similarity to Curtovirus Reps (48.5-69.0 %); however, in the case of the capsid protein (CP), the extent of similarity is only 39.5-44.5 %. We constructed an agroinfectious clone of TCTV and undertook host range studies on ten plant species; in three species (turnip, sugar beet and cowpea), we detected infection which presents curly top symptoms in turnip and sugar beet. The efficiency of TCTV infection in agroinoculated turnip plants was 71.7 %, and the infection was successfully transmitted to 80 % of the healthy turnip plants used in the insect trans- mission studies by Circulifer haematoceps under green- house conditions. We also determined the genome sequence of 14 new TCTV isolates from southern Iran isolated from turnips. We observed *13 % diversity amongst all the TCTV isolates and found evidence of recombination in the CP- and Rep-coding regions of the genomes.
Robert L Gilbertson - One of the best experts on this subject based on the ideXlab platform.
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Genetic diversity in Curtoviruses: a highly divergent strain of Beet mild curly top virus associated with an outbreak of curly top disease in pepper in Mexico
Archives of Virology, 2011Co-Authors: L.-f. Chen, E. Vivoda, Robert L GilbertsonAbstract:A full-length Curtovirus genome was PCR-amplified and cloned from peppers in Mexico with symptoms of curly top disease. The cloned DNA of this isolate, MX-P24, replicated in Nicotiana tabacum protoplasts and was infectious in N. benthamiana plants. Sequence analysis revealed that the MX-P24 isolate had a typical Curtovirus genome organization and was most similar to beet mild curly top virus (BMCTV). However, sequence identities were at the threshold value for establishment of a new Curtovirus species. To further investigate the biological properties of MX-P24, an agroinoculation system was generated. Agroinoculated shepherd’s purse plants developed typical curly top symptoms, and virus from these plants was transmissible by the beet leafhopper ( Circulifer tenellus ). The host range of MX-P24 was similar to that of BMCTV, with curly top symptoms induced in common bean, pepper, pumpkin, shepherd’s purse and tomato plants and mild or no symptoms induced in sugar beet plants. Together, these results indicate that MX-P24 is a highly divergent strain of BMCTV associated with an outbreak of curly top disease in peppers in Mexico.
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Quantitative Resistance to Bean dwarf mosaic virus in Common Bean Is Associated with the Bct Gene for Resistance to Beet curly top virus
Plant disease, 2009Co-Authors: Phillip N. Miklas, Young-su Seo, Robert L GilbertsonAbstract:The dominant resistance gene, Bct, in common bean (Phaseolus vulgaris) confers qualitative resistance to Beet curly top virus, a leafhopper-transmitted geminivirus in the genus Curtovirus. To determine whether this gene confers resistance to other geminiviruses, bean plants of a recombinant inbred population were sap-inoculated with Bean dwarf mosaic virus (BDMV), a whitefly-transmitted bipartite begomovirus in the genus Begomovirus. Results indicated that Bct (or tightly linked gene) is associated with quantitative resistance to BDMV; thus, the Bct locus is associated with resistance to a bean-infecting begomovirus and Curtovirus. The difference in the nature of the resistance to these geminiviruses may indicate a role for minor genes in begomovirus resistance or differences in the virus-host interaction. The Bct locus, whether it acts alone or represents a cluster of tightly linked genes, will be useful in breeding for broad-spectrum begomovirus resistance in common bean.
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Curtovirus-cucurbit interaction: acquisition host plays a role in leafhopper transmission in a host-dependent manner.
Phytopathology, 2009Co-Authors: L.-f. Chen, Robert L GilbertsonAbstract:Curly top disease (CTD) of vegetable crops is caused by viruses in the genus Curtovirus (family Geminiviridae). Cucurbits are reported to be susceptible to CTD; however, the disease is rare in California despite annual outbreaks in other hosts (e.g., common bean, pepper, sugar beet, and tomato). Consistent with these observations, no obvious curly top symptoms were observed in melon fields surveyed for CTD in Central California in 2004 and 2005, whereas the disease was readily observed in tomato plants in nearby fields. However, samples of cucurbits from Idaho with curly top-like symptoms, collected in 2005 and 2007, were confirmed to have the disease. The susceptibility of cucurbits (cantaloupe, honeydew melon, pumpkin, and watermelon) to the three Curtoviruses known to occur in California (Beet curly top virus, BCTV; Beet severe curly top virus, BSCTV; and Beet mild curly top virus, BMCTV) was evaluated by agroinoculation or leafhopper transmission. Irrespective of the Curtovirus species and inoculation method, low rates of infection and mild or symptomless disease phenotypes were observed in cucurbits. In contrast, all inoculated tomato, Nicotiana benthamiana, or shepherd's purse plants were infected and developed severe symptoms. In leafhopper transmission experiments, BMCTV infected cucurbits when leafhoppers acquired the virus from a symptomatic host with a high viral titer (shepherd's purse), whereas no infection occurred when the acquisition host had mild symptoms and a low viral titer (sugar beet); in contrast, the acquisition host did not influence transmission of BMCTV to tomato or shepherd's purse (all plants were infected). This revealed an influence of the acquisition host on leafhopper transmission in a host-specific manner. Our results also indicate that, although cucurbits can develop CTD, they are relatively poor hosts for these Curtoviruses.
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identification of regions of the beet mild curly top virus family geminiviridae capsid protein involved in systemic infection virion formation and leafhopper transmission
Virology, 2005Co-Authors: Maria J Soto, L.-f. Chen, Robert L GilbertsonAbstract:Plant viruses in the genus Curtovirus (family Geminiviridae) are vectored by the beet leafhopper (Circulifer tenellus) and cause curly top disease in a wide range of dicotyledonous plants. An infectious clone of an isolate of Beet mild curly top virus (BMCTV-[W4]), associated with an outbreak of curly top in pepper and tomato crops, was characterized and used to investigate the role of the capsid protein (CP) in viral biology and pathogenesis. Frameshift mutations were introduced into the overlapping CP and V2 genes, and a series of CP alanine scanning mutations were generated. All mutants replicated in tobacco protoplasts or systemically infected plants, consistent with these gene products not being required for viral DNA replication. The CP frameshift mutant and most C-terminal alanine scanning mutants did not systemically infect Nicotiana benthamiana plants or form detectable virions, and were not leafhopper-transmitted. In contrast, most N-terminal alanine scanning mutants systemically infected N. benthamiana and induced disease symptoms, formed virions and were leafhopper-transmissible; thus, these substitution mutations did not significantly alter the functional properties of this region. One N-terminal mutant (CP49-51) systemically infected N. benthamiana, but did not form detectable virions; whereas another (CP25-28) systemically infected N. benthamiana and formed virions, but was not insect-transmissible. These mutants may reveal regions involved in virus movement through the plant and/or leafhopper vector. Together, these results indicate an important role for virions in systemic infection (long-distance movement) and insect transmission, and strongly suggest that virions are the form in which BMCTV moves, long distance, in the phloem.
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distribution and rate of movement of the Curtovirus beet mild curly top virus family geminiviridae in the beet leafhopper
Phytopathology, 2003Co-Authors: Maria J Soto, Robert L GilbertsonAbstract:ABSTRACT A polymerase chain reaction (PCR)-based method for the detection of the Curtovirus Beet mild curly top virus (BMCTV, previously named the Worland strain of Beet curly top virus) was developed and used to investigate the BMCTV-beet leafhopper interaction. Using PCR and a BMCTV-specific primer pair, an ≈1.1-kb BMCTV DNA fragment was amplified from adult leafhoppers and from the organs involved in circulative transmission: the digestive tract, hemolymph, and salivary glands. The temporal distribution of BMCTV in the leafhopper was determined using insects given acquisition access periods (AAPs) ranging from 1 to 48 h on BMCTV-infected shepherd's purse plants. BMCTV was detected in the digestive tract after all AAPs, in the hemolymph after AAPs of 3 h or greater, and in the salivary glands after AAPs of 4 h or greater. The amount of virus detected in the hemolymph and salivary glands increased with AAP length. The virus persisted for up to 30 days in leafhoppers (given a 3-day AAP on BMCTV-infected p...
Rob W Briddon - One of the best experts on this subject based on the ideXlab platform.
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ICTV Virus Taxonomy Profile: Geminiviridae
Journal of General Virology, 2017Co-Authors: F. Murilo Zerbini, Rob W Briddon, Ali M. Idris, Darren P. Martin, Philippe Roumagnac, Rafael F. Rivera-bustamante, Enrique Moriones, Jesús Navas-castillo, Arvind VarsaniAbstract:The geminiviruses are a family of small, non-enveloped viruses with single-stranded, circular DNA genomes of 2500–5200 bases. Geminiviruses are transmitted by various types of insect (whiteflies, leafhoppers, treehoppers and aphids). Members of the genus Begomovirus are transmitted by whiteflies, those in the genera BeCurtovirus, Curtovirus, Grablovirus, Mastrevirus and TurnCurtovirus are transmitted by specific leafhoppers, the single member of the genus Topocuvirus is transmitted by a treehopper and one member of the genus Capulavirus is transmitted by an aphid. Geminiviruses are plant pathogens causing economically important diseases in most tropical and subtropical regions of the world. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Geminiviridae which is available at www.ictv.global/report/geminiviridae.
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Capulavirus and Grablovirus: two new genera in the family Geminiviridae.
Archives of Virology, 2017Co-Authors: Arvind Varsani, Rob W Briddon, Philippe Roumagnac, Rafael F. Rivera-bustamante, Enrique Moriones, Jesús Navas-castillo, Marc Fuchs, Ali Idris, F Murilo Zerbini, Darren P. MartinAbstract:Geminiviruses are plant-infecting single-stranded DNA viruses that occur in most parts of the world. Currently, there are seven genera within the family Geminiviridae (BeCurtovirus, Begomovirus, Curtovirus, Eragrovirus, Mastrevirus, Topocuvirus and TurnCurtovirus). The rate of discovery of new geminiviruses has increased significantly over the last decade as a result of new molecular tools and approaches (rolling-circle amplification and deep sequencing) that allow for high-throughput workflows. Here, we report the establishment of two new genera: Capulavirus, with four new species (Alfalfa leaf curl virus, Euphorbia caput-medusae latent virus, French bean severe leaf curl virus and Plantago lanceolata latent virus), and Grablovirus, with one new species (Grapevine red blotch virus). The aphid species Aphis craccivora has been shown to be a vector for Alfalfa leaf curl virus, and the treehopper species Spissistilus festinus is the likely vector of Grapevine red blotch virus. In addition, two highly divergent groups of viruses found infecting citrus and mulberry plants have been assigned to the new species Citrus chlorotic dwarf associated virus and Mulberry mosaic dwarf associated virus, respectively. These species have been left unassigned to a genus by the ICTV because their particle morphology and insect vectors are unknown.
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Revision of Begomovirus taxonomy based on pairwise sequence comparisons
Archives of virology, 2015Co-Authors: Judith K. Brown, F. Murilo Zerbini, Rob W Briddon, Cecilia Hernández-zepeda, Enrique Moriones, Jesús Navas-castillo, Elvira Fiallo-olivé, Roberto Ramos-sobrinho, José C. F. Silva, Ali M. IdrisAbstract:Viruses of the genus Begomovirus (family Geminiviridae) are emergent pathogens of crops throughout the tropical and subtropical regions of the world. By virtue of having a small DNA genome that is easily cloned, and due to the recent innovations in cloning and low-cost sequencing, there has been a dramatic increase in the number of available begomovirus genome sequences. Even so, most of the available sequences have been obtained from cultivated plants and are likely a small and phylogenetically unrepresentative sample of begomovirus diversity, a factor constraining taxonomic decisions such as the establishment of operationally useful species demarcation criteria. In addition, problems in assigning new viruses to established species have highlighted shortcomings in the previously recommended mechanism of species demarcation. Based on the analysis of 3,123 full-length begomovirus genome (or DNA-A component) sequences available in public databases as of December 2012, a set of revised guidelines for the classification and nomenclature of begomoviruses are proposed. The guidelines primarily consider a) genus-level biological characteristics and b) results obtained using a standardized classification tool, Sequence Demarcation Tool, which performs pairwise sequence alignments and identity calculations. These guidelines are consistent with the recently published recommendations for the genera Mastrevirus and Curtovirus of the family Geminiviridae. Genome-wide pairwise identities of 91 % and 94 % are proposed as the demarcation threshold for begomoviruses belonging to different species and strains, respectively. Procedures and guidelines are outlined for resolving conflicts that may arise when assigning species and strains to categories wherever the pairwise identity falls on or very near the demarcation threshold value.
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Turnip curly top virus, a highly divergent geminivirus infecting turnip in Iran.
Virus research, 2010Co-Authors: Rob W Briddon, Darren P. Martin, Jahangir Heydarnejad, Hossain Massumi, Fakhrosadat Khosrowfar, Arvind VarsaniAbstract:From 2006 onwards turnip crops in Fars province, Iran, have been noted with unusual leaf curling and vein swelling symptoms which are characteristic of the leafhopper-transmitted viruses of the genus Curtovirus (family Geminiviridae). Rolling circle amplification was used to clone viruses from five turnip isolates exhibiting leaf curl symptoms. Analysis of the sequences showed them to have >93% sequence identity and to be distinct from all other geminiviruses previously characterised. Analysis of the sequence of this virus, for which we propose the name Turnip curly top virus (TCTV), showed it to have a genome arrangement in the complementary-sense similar to that of Curtoviruses (consisting of four overlapping genes) but only two open reading frames in the virion-sense (the Curtoviruses encode three). The complementary-sense genes are homologous to those of Curtoviruses but show little sequence identity to their Curtovirus homologs, with the exception of the product of the C4 open reading frame (ORF) which shows approximately 70.6% amino acid sequence identity to the C4 of the North American Curtoviruses, Pepper curly top virus and Beet mild curly top virus. For Curtoviruses the C4 protein is a symptom determinant, which likely explains the similarity of TCTV symptoms to those of Curtoviruses. In the virion-sense the predicted product of the V2 ORF of TCTV shows no significant similarity with any proteins in the databases whereas the product of the V1 ORF (encoding the coat protein [CP] of geminiviruses) shows low levels of sequence identity to the CPs of Curtoviruses. These findings show TCTV to be a highly divergent geminivirus with similarities to viruses of the genus Curtovirus. The significance of these findings, particularly the taxonomic implications are discussed.
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Revision of taxonomic criteria for species demarcation in the family Geminiviridae, and an updated list of begomovirus species.
Archives of virology, 2003Co-Authors: Claude M. Fauquet, Rob W Briddon, Judith K. Brown, Drake C. Stenger, D. M. Bisaro, Bryan D. Harrison, Edward P. Rybicki, John StanleyAbstract:Members of the family Geminiviridae characteristically have circular single-stranded DNAgenomes packaged within twinned (so-called geminate) particles. Geminiviruses are currentlydivided into four genera on the basis of their genome organizations and biological properties[2,20].Thosethathaveamonopartitegenomeandaretransmittedbyleafhoppervectors,primarilyto monocotyledonous plants, are included in the genus Mastrevirus, of which Maize streak virus isthe type species. Viruses that have monopartite genomes distinct from those of the mastrevirusesand that are transmitted by leafhopper vectors to dicotyledonous plants are included in thegenus Curtovirus, with Beet curly top virus as the type species. The genus Topocuvirus, recentlyrecognized by the International Committee on Taxonomy of Viruses (ICTV) [18], has only onemember (also the type species), Tomato pseudo-curly top virus, which has a monopartite genomeandistransmittedbyatreehoppervectortodicotyledonousplants.ThegenusBegomoviruscontainsviruses that are transmitted by the whitefly Bemisia tabaci (Gennadius) to dicotyledonous plants,with Bean golden yellow mosaic virus (originally Bean golden mosaic virus – Puerto Rico)asthetype species. Many begomoviruses have bipartite genomes (DNA A and DNA B components),although numerous begomoviruses with a monopartite genome occur in the Old World, and thereare some for which a single component is not infectious yet no DNA B component has been found.Geminiviruses cause significant yield losses to many crop plants throughout the world [5, 7].Because of their economic importance and the relative ease with which their DNA genomescan be cloned, many geminiviruses have been isolated and characterized. Guidelines for naming
John Stanley - One of the best experts on this subject based on the ideXlab platform.
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Beet Curly Top Virus
Encyclopedia of Virology, 2008Co-Authors: John StanleyAbstract:Curly top disease affects a wide variety of vegetables and weeds in western states of the USA and the Mediterranean Basin and is caused by viruses belonging to the genus Curtovirus in the family Geminiviridae. Originally considered to be strains of Beet curly top virus because of their similar phenotypes, the genus now contains four additional species, Beet mild curly top virus, Beet severe curly top virus, Horseradish curly top virus, and Spinach curly top virus. All Curtoviruses are transmitted by the leafhopper Circulifer tenellus (Baker) in a circulative, nonpropagative manner. Beet curly top virus (BCTV) has a small circular single-stranded genomic DNA encapsidated in twinned quasi-isometric particles that is a feature of all geminiviruses. The genome encodes seven proteins required for replication (C1/Rep and C3/REn), movement and insect transmission (V1/CP, V2 and V3), and pathogenicity (C2 and C4). The viral DNA accumulates by rolling-circle and recombination-dependent replication strategies. BCTV is tightly phloem-limited and induces cell division and expansion in affected tissues that precedes necrosis and eventual collapse of the phloem, resulting in characteristic leaf curling and vein-swelling symptoms.
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Revision of taxonomic criteria for species demarcation in the family Geminiviridae, and an updated list of begomovirus species.
Archives of virology, 2003Co-Authors: Claude M. Fauquet, Rob W Briddon, Judith K. Brown, Drake C. Stenger, D. M. Bisaro, Bryan D. Harrison, Edward P. Rybicki, John StanleyAbstract:Members of the family Geminiviridae characteristically have circular single-stranded DNAgenomes packaged within twinned (so-called geminate) particles. Geminiviruses are currentlydivided into four genera on the basis of their genome organizations and biological properties[2,20].Thosethathaveamonopartitegenomeandaretransmittedbyleafhoppervectors,primarilyto monocotyledonous plants, are included in the genus Mastrevirus, of which Maize streak virus isthe type species. Viruses that have monopartite genomes distinct from those of the mastrevirusesand that are transmitted by leafhopper vectors to dicotyledonous plants are included in thegenus Curtovirus, with Beet curly top virus as the type species. The genus Topocuvirus, recentlyrecognized by the International Committee on Taxonomy of Viruses (ICTV) [18], has only onemember (also the type species), Tomato pseudo-curly top virus, which has a monopartite genomeandistransmittedbyatreehoppervectortodicotyledonousplants.ThegenusBegomoviruscontainsviruses that are transmitted by the whitefly Bemisia tabaci (Gennadius) to dicotyledonous plants,with Bean golden yellow mosaic virus (originally Bean golden mosaic virus – Puerto Rico)asthetype species. Many begomoviruses have bipartite genomes (DNA A and DNA B components),although numerous begomoviruses with a monopartite genome occur in the Old World, and thereare some for which a single component is not infectious yet no DNA B component has been found.Geminiviruses cause significant yield losses to many crop plants throughout the world [5, 7].Because of their economic importance and the relative ease with which their DNA genomescan be cloned, many geminiviruses have been isolated and characterized. Guidelines for naming
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Adaptation from whitefly to leafhopper transmission of an autonomously replicating nanovirus-like DNA component associated with ageratum yellow vein disease
Journal of General Virology, 2002Co-Authors: Keith Saunders, Ian D. Bedford, John StanleyAbstract:Ageratum yellow vein disease is caused by the whitefly-transmitted monopartite begomovirus Ageratum yellow vein virus and a DNA β satellite component. Naturally occurring symptomatic plants also contain an autonomously replicating nanovirus-like DNA 1 component that relies on the begomovirus and DNA β for systemic spread and whitefly transmission but is not required for maintenance of the disease. Here, we show that systemic movement of DNA 1 occurs in Nicotiana benthamiana when co-inoculated with the bipartite begomovirus Tomato golden mosaic virus and the Curtovirus Beet curly top virus (BCTV), but not with the mastrevirus Bean yellow dwarf virus. BCTV also mediates the systemic movement of DNA 1 in sugar beet, and the nanovirus-like component is transmitted between plants by the BCTV leafhopper vector Circulifer tenellus. We also describe a second nanovirus-like component, referred to as DNA 2, that has only 47% nucleotide sequence identity with DNA 1. The diversity and adaptation of nanovirus components are discussed.
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Adaptation from whitefly to leafhopper transmission of an autonomously replicating nanovirus-like DNA component associated with ageratum yellow vein disease.
The Journal of general virology, 2002Co-Authors: Keith Saunders, Ian D. Bedford, John StanleyAbstract:Ageratum yellow vein disease is caused by the whitefly-transmitted monopartite begomovirus Ageratum yellow vein virus and a DNA beta satellite component. Naturally occurring symptomatic plants also contain an autonomously replicating nanovirus-like DNA 1 component that relies on the begomovirus and DNA beta for systemic spread and whitefly transmission but is not required for maintenance of the disease. Here, we show that systemic movement of DNA 1 occurs in Nicotiana benthamiana when co-inoculated with the bipartite begomovirus Tomato golden mosaic virus and the Curtovirus Beet curly top virus (BCTV), but not with the mastrevirus Bean yellow dwarf virus. BCTV also mediates the systemic movement of DNA 1 in sugar beet, and the nanovirus-like component is transmitted between plants by the BCTV leafhopper vector Circulifer tenellus. We also describe a second nanovirus-like component, referred to as DNA 2, that has only 47% nucleotide sequence identity with DNA 1. The diversity and adaptation of nanovirus components are discussed.
Jesús Navas-castillo - One of the best experts on this subject based on the ideXlab platform.
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ICTV Virus Taxonomy Profile: Geminiviridae
Journal of General Virology, 2017Co-Authors: F. Murilo Zerbini, Rob W Briddon, Ali M. Idris, Darren P. Martin, Philippe Roumagnac, Rafael F. Rivera-bustamante, Enrique Moriones, Jesús Navas-castillo, Arvind VarsaniAbstract:The geminiviruses are a family of small, non-enveloped viruses with single-stranded, circular DNA genomes of 2500–5200 bases. Geminiviruses are transmitted by various types of insect (whiteflies, leafhoppers, treehoppers and aphids). Members of the genus Begomovirus are transmitted by whiteflies, those in the genera BeCurtovirus, Curtovirus, Grablovirus, Mastrevirus and TurnCurtovirus are transmitted by specific leafhoppers, the single member of the genus Topocuvirus is transmitted by a treehopper and one member of the genus Capulavirus is transmitted by an aphid. Geminiviruses are plant pathogens causing economically important diseases in most tropical and subtropical regions of the world. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Geminiviridae which is available at www.ictv.global/report/geminiviridae.
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Capulavirus and Grablovirus: two new genera in the family Geminiviridae.
Archives of Virology, 2017Co-Authors: Arvind Varsani, Rob W Briddon, Philippe Roumagnac, Rafael F. Rivera-bustamante, Enrique Moriones, Jesús Navas-castillo, Marc Fuchs, Ali Idris, F Murilo Zerbini, Darren P. MartinAbstract:Geminiviruses are plant-infecting single-stranded DNA viruses that occur in most parts of the world. Currently, there are seven genera within the family Geminiviridae (BeCurtovirus, Begomovirus, Curtovirus, Eragrovirus, Mastrevirus, Topocuvirus and TurnCurtovirus). The rate of discovery of new geminiviruses has increased significantly over the last decade as a result of new molecular tools and approaches (rolling-circle amplification and deep sequencing) that allow for high-throughput workflows. Here, we report the establishment of two new genera: Capulavirus, with four new species (Alfalfa leaf curl virus, Euphorbia caput-medusae latent virus, French bean severe leaf curl virus and Plantago lanceolata latent virus), and Grablovirus, with one new species (Grapevine red blotch virus). The aphid species Aphis craccivora has been shown to be a vector for Alfalfa leaf curl virus, and the treehopper species Spissistilus festinus is the likely vector of Grapevine red blotch virus. In addition, two highly divergent groups of viruses found infecting citrus and mulberry plants have been assigned to the new species Citrus chlorotic dwarf associated virus and Mulberry mosaic dwarf associated virus, respectively. These species have been left unassigned to a genus by the ICTV because their particle morphology and insect vectors are unknown.
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Deciphering the biology of deltasatellites from the New World: maintenance by New World begomoviruses and whitefly transmission
The New phytologist, 2016Co-Authors: Elvira Fiallo-olivé, Remedios Tovar, Jesús Navas-castilloAbstract:Deltasatellites are small noncoding DNA satellites associated with begomoviruses. The study presented here has investigated the biology of two deltasatellites found in wild malvaceous plants in the New World (NW). Infectious clones of two NW deltasatellites (from Malvastrum coromandelianum and Sidastrum micranthum) and associated begomoviruses were constructed. Infectivity in Nicotiana benthamiana and their natural malvaceous hosts was assessed. The NW deltasatellites were not able to spread autonomously in planta, whereas they were maintained by the associated bipartite begomovirus. Furthermore, NW deltasatellites were transreplicated by a monopartite NW begomovirus, tomato leaf deformation virus. However, they were not maintained by begomoviruses from the Old World (tomato yellow leaf curl virus, tomato yellow leaf curl Sardinia virus and African cassava mosaic virus) or a Curtovirus (beet curly top virus). NW deltasatellites did not affect the symptoms induced by the helper viruses but in some cases reduced their accumulation. Moreover, one NW deltasatellite was shown to be transmitted by the whitefly Bemisia tabaci, the vector of its helper begomoviruses. These results confirm that these molecules are true satellites. The availability of infectious clones and the observation that NW deltasatellites reduced virus accumulation paves the way for further studies of the effect on their helper begomoviruses.
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Revision of Begomovirus taxonomy based on pairwise sequence comparisons
Archives of virology, 2015Co-Authors: Judith K. Brown, F. Murilo Zerbini, Rob W Briddon, Cecilia Hernández-zepeda, Enrique Moriones, Jesús Navas-castillo, Elvira Fiallo-olivé, Roberto Ramos-sobrinho, José C. F. Silva, Ali M. IdrisAbstract:Viruses of the genus Begomovirus (family Geminiviridae) are emergent pathogens of crops throughout the tropical and subtropical regions of the world. By virtue of having a small DNA genome that is easily cloned, and due to the recent innovations in cloning and low-cost sequencing, there has been a dramatic increase in the number of available begomovirus genome sequences. Even so, most of the available sequences have been obtained from cultivated plants and are likely a small and phylogenetically unrepresentative sample of begomovirus diversity, a factor constraining taxonomic decisions such as the establishment of operationally useful species demarcation criteria. In addition, problems in assigning new viruses to established species have highlighted shortcomings in the previously recommended mechanism of species demarcation. Based on the analysis of 3,123 full-length begomovirus genome (or DNA-A component) sequences available in public databases as of December 2012, a set of revised guidelines for the classification and nomenclature of begomoviruses are proposed. The guidelines primarily consider a) genus-level biological characteristics and b) results obtained using a standardized classification tool, Sequence Demarcation Tool, which performs pairwise sequence alignments and identity calculations. These guidelines are consistent with the recently published recommendations for the genera Mastrevirus and Curtovirus of the family Geminiviridae. Genome-wide pairwise identities of 91 % and 94 % are proposed as the demarcation threshold for begomoviruses belonging to different species and strains, respectively. Procedures and guidelines are outlined for resolving conflicts that may arise when assigning species and strains to categories wherever the pairwise identity falls on or very near the demarcation threshold value.
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Revisiting the classification of Curtoviruses based on genome-wide pairwise identity
Archives of virology, 2014Co-Authors: Arvind Varsani, F. Murilo Zerbini, Cecilia Hernández-zepeda, Ali M. Idris, Darren P. Martin, Enrique Moriones, Jesús Navas-castillo, Judith K. BrownAbstract:Members of the genus Curtovirus (family Geminiviridae) are important pathogens of many wild and cultivated plant species. Until recently, relatively few full Curtovirus genomes have been characterised. However, with the 19 full genome sequences now available in public databases, we revisit the proposed Curtovirus species and strain classification criteria. Using pairwise identities coupled with phylogenetic evidence, revised species and strain demarcation guidelines have been instituted. Specifically, we have established 77 % genome-wide pairwise identity as a species demarcation threshold and 94 % genome-wide pairwise identity as a strain demarcation threshold. Hence, whereas Curtovirus sequences with >77 % genome-wide pairwise identity would be classified as belonging to the same species, those sharing >94 % identity would be classified as belonging to the same strain. We provide step-by-step guidelines to facilitate the classification of newly discovered Curtovirus full genome sequences and a set of defined criteria for naming new species and strains. The revision yields three Curtovirus species: Beet curly top virus (BCTV), Spinach severe surly top virus (SpSCTV) and Horseradish curly top virus (HrCTV).
